September 1992 arXiv papers — page 2

Darwin Chang, Wai-Yee Keung, Ivan Phillips

We investigate a possible CP violating effect in $e^+e^-$ annihilation into $t\bar t$ top quark pairs. As an illustrative example, we assume the source of the CP nonconservation is in the Yukawa couplings of a neutral Higgs boson which contain both scalar and pseudoscalar pieces. One of the interesting observable effects is the difference in production rates

V. G. Bornyakov, V. K. Mitrjushkin, M. Müller-Preussker

We study properties of the compact $~4D~$ $U(1)$ lattice gauge theory with monopoles {\it removed}. Employing Monte Carlo simulations we calculate correlators of scalar, vector and tensor operators at zero and nonzero momenta $~\vec{p}~$. We confirm that the theory without monopoles has no phase transition, at least, in the interval $~0 < β\leq 2~$. There th

E. E. Donets, D. V. Gal&#39;tsov

It is shown that for some particular value of the cosmological constant depending on the gauge coupling constant a continuous one-parameter family of Einstein-Yang-Mills wormholes exists which interpolates between the instanton and the gravitating meron solutions. In contradistinction with the previously known solutions the topological charge of these wormho

A. H. Castro Neto, A. O. Caldeira

We developed a new method based on functional integration to treat the dynamics of polarons in one-dimensional systems. We treat the acoustical and the optical case in an unified manner, showing their differences and similarities. The mobility and diffusion coefficients are calculated in the Markovian approximation in the strong coupling limit.

Valerio Faraoni, Sebastiano Sonego

The tail problem for the propagation of a scalar field is considered in a cosmological background, taking a Robertson-Walker spacetime as a specific example. The explicit radial dependence of the general solution of the Klein-Gordon equation with nonminimal coupling is derived, and the inapplicability of the standard calculation of the reflection and transmi

Samson L. Shatashvili

The n-point function for the integral over unitary matrices with Itzykson-Zuber measure is reduced to the integral over Gelfand-Tzetlin table; integrand (for generic n) is given by linear exponential times rational function. For $n=2$ and in some cases for $n>2$ later in fact is the polinomial and this allows to give an explicit and simple expression for all

Fernando Falceto, Krzysztof Gawedzki

Quantum groups play a role of symmetries of integrable theories in two dimensions. They may be detected on the classical level as Poisson-Lie symmetries of the corresponding phase spaces. We discuss specifically the Wess-Zumino-Witten conformally invariant quantum field model combining two chiral parts which describe the left- and right-moving degrees of fre

William B. Johnson, Gideon Schechtman

It is shown that the p-summing norm of any operator with n-dimensional domain can be well-aproximated using only ``few&#34; vectors in the definition of the p-summing norm. Except for constants independent of n and log n factors, ``few&#34; means n if 1<p<2 and n^{p/2} if 2<p<infinity.

D. M. Gitman, A. V. Saa

A generalization of the pseudoclassical action of a spinning particle in the presence of an anomalous magnetic moment is given. The leading considerations, to write the action, are gotten from the path integral representation for the causal Green&#39;s function of the generalized (by Pauli) Dirac equation for the particle with anomalous magnetic momentum in

S. Cecotti, C. Vafa

We establish a direct link between massive Ising model and arbitrary massive $N=2$ supersymmetric QFT&#39;s in two dimensions. This explains why the equations which appear in the computation of spin-correlations in the non-critical Ising model are the same as those describing the geometry of vacua in $N=2$ theories. The tau-function appearing in the Ising mo

Ashok Das, C. A. P. Galvao

We derive the entire KdV hierarchy as well as the recursion relations from the self-duality condition on gauge fields in four dimensions.

Alexander Turbiner

Classification theorems for linear differential equations in two real variables, possessing eigenfunctions in the form of the polynomials (the generalized Bochner problem) are given. The main result is based on the consideration of the eigenvalue problem for a polynomial elements of the universal enveloping algebras of the algebras $sl_3({\bf R})$, $sl_2({\b

R. Brustein, B. Ovrut

We discuss continuous and discrete sectors in the collective field theory of $d=1$ matrix models. A canonical Lorentz invariant field theory extension of collective field theory is presented and its classical solutions in Euclidean and Minkowski space are found. We show that the discrete, low density, sector of collective field theory includes single eigenva

Alexander Turbiner

A classification theorem for linear differential equations in two variables (one real and one Grassmann) having polynomial solutions(the generalized Bochner problem) is given. The main result is based on the consideration of the eigenvalue problem for a polynomial element of the universal enveloping algebra of the algebra $osp(2,2)$ in the &#34;projectivized

Alexander Turbiner

A classification of ordinary differential equations and finite-difference equations in one variable having polynomial solutions (the generalized Bochner problem) is given. The method used is based on the spectral problem for a polynomial element of the universal enveloping algebra of $sl_2({\bf R})$ (for differential equations) or $sl_2({\bf R})_q$ (for fini

Francois Gieres

For a generic value of the central charge, we prove the holomorphic factorization of partition functions for free superconformal fields which are defined on a compact Riemann surface without boundary. The partition functions are viewed as functionals of the Beltrami coefficients and their fermionic partners which variables parametrize superconformal classes

A. Turbiner

A general method of obtaining linear differential equations having polynomial solutions is proposed. The method is based on an equivalence of the spectral problem for an element of the universal enveloping algebra of some Lie algebra in the &#34;projectivized&#34; representation possessing an invariant subspace and the spectral problem for a certain linear d

Alex Deckmyn

By generalizing the Miura transformation for $\Ww_N$ to other classical $\Ww$ algebras obtained by hamiltonian reduction, we find realisations of these algebras in terms of relatively simple non-abelian current algebras, e.g. $\widehat{sl(2)}\times \widehat{u(1)}^N$, generalizing the free field realisation of $\Ww_N$. As an example, we present the $\widehat{

Patrick Labelle

This is a pedagogical introduction to NRQED, a low enery approximation of QED which can be made to reproduce QED to an arbitrary precision. It is especially useful when applied to nonrelativistic bound states. We start by explaining why QED is so difficult to apply to nr bound states, why NRQED makes it much simpler and then proceed to do an explicit calcula

F. T. Brandt, J. Frenkel

The high temperature limit of the 3-graviton vertex function is studied in thermal quantum gravity, to one loop order. The leading ($T^4$) contributions arising from internal gravitons are calculated and shown to be twice the ones associated with internal scalar particles, in correspondence with the two helicity states of the graviton. The gauge invariance o

S. Y. Choi, H. S. Song

The spin and flavor symmetries of the heavy quark effective theory are employed to discuss the exclusive cross sections for pair production of heavy mesons in photon-photon collision. The ratios of the exclusive cross sections for heavy mesons are obtained explicitly and the validity of results is discussed.

James F. Amundson, Jonathan L. Rosner

The decays of $D$ mesons to $K l ν$ and $K^* l ν$ final states exhibit significant deviations from the predictions of heavy-quark symmetry, as one might expect since the strange quark&#39;s mass is of the same order as the QCD scale. Nonetheless, in order to understand where the most significant effects might lie for heavier systems (such as $B \to D lν$ and

G. P. Lepage, P. B. Mackenzie

In this paper we show that the apparent failure of QCD lattice perturbation theory to account for Monte Carlo measurements of perturbative quantities results from choosing the bare lattice coupling constant as the expansion parameter. Using instead ``renormalized&#39;&#39; coupling constants defined in terms of physical quantities, like the heavy-quark poten

A. Morozov

An explicit expression is suggested for the average $<U_{ij}U_{kl}^{\dagger}>$ over the unitary group $SU(N)$ with the Itzykson-Zuber measure $[dU] \exp {\rm tr} ΦUΨU^{\dagger}$

Lev Rozansky, Herbert Saleur

We show that the $U(1,1)$ (super) Chern Simons theory is one loop exact. This provides a direct proof of the relation between the Alexander polynomial and analytic and Reidemeister torsion. We then proceed to compute explicitely the torsions of Lens spaces and Seifert manifolds using surgery and the $S$ and $T$ matrices of the $U(1,1)$ Wess Zumino Witten mod

Malcolm J. Perry, Edward Teo

We incorporate both BRS symmetry and anti-BRS symmetry into the quantisation of topological Yang--Mills theory. This refines previous treatments which consider only the BRS symmetry. Our formalism brings out very clearly the geometrical meaning of topological Yang--Mills theory in terms of connections and curvatures in an enlarged superspace; and its simple

H. Y. Cheng, C. Y. Cheung, G. L. Lin, Y. C. Lin

The radiative decays of heavy mesons and heavy baryons are studied in a formalism which incorporates both the heavy quark symmetry and the chiral symmetry. The chiral Lagrangians for the electromagnetic interactions of heavy hadrons consist of two pieces: one from gauging electromagnetically the strong-interaction chiral Lagrangian, and the other from the an

J. Bijnens, G. Ecker, J. Gasser

We evaluate the matrix elements for the radiative kaon decays $K^+ \to l^+ν_lγ$, $l^+ ν_l l&#39;^+ l&#39;^-$ and $K \to πl ν_lγ$ \ ($l,\ l&#39; = e,μ$) to next-to-leading order in chiral perturbation theory. We calculate total rates and rates with several kinematical cuts and confront the results with existing data. Measurements at future kaon facilities wil

X. G. He, J. P. Ma, B. H. J. McKellar

In this paper we calculate the one loop contributions to the CP violating three gauge boson couplings in two-Higgs doublet and Left--Right symmetric models. In the two-Higgs doublet model only a P conserving and CP violating coupling is generated, and it can be large as $10^{-3}$. In the Left--Right symmetric model both P conserving and violating couplings a

M. Baeker, T. Kalkreuter, G. Mack, M. Speh

We present evidence that multigrid works for wave equations in disordered systems, e.g. in the presence of gauge fields, no matter how strong the disorder, but one needs to introduce a &#34;neural computations&#34; point of view into large scale simulations: First, the system must learn how to do the simulations efficiently, then do the simulation (fast). Th

John W. Milnor

This will is an expository description of quadratic rational maps. Sections 2 through 6 are concerned with the geometry and topology of such maps. Sections 7--10 survey of some topics from the dynamics of quadratic rational maps. There are few proofs. Section 9 attempts to explore and picture moduli space by means of complex one-dimensional slices. Section 1

R. Foot, H. Lew, R. R. Volkas

Experimentally it has been known for a long time that the electric charges of the observed particles appear to be quantized. An approach to understanding electric charge quantization that can be used for gauge theories with explicit $U(1)$ factors -- such as the standard model and its variants -- is pedagogically reviewed and discussed in this article. This

Greg W. Anderson

In the standard scenario, the electroweak phase transition is a first order phase transition which completes by the nucleation of critical bubbles. Recently, there has been speculation that the standard picture of the electroweak phase transition is incorrect. Instead, it has been proposed that throughout the phase transition appreciable amounts of both brok

Steven Weinberg

A chiral invariant effective Lagrangian may be used to calculate the three-body interactions among low-energy pions and nucleons in terms of known parameters. This method is illustrated by the calculation of the pion-nucleus scattering length.

Kikuo Harigaya

We review the recent theoretical treatment of fullerenes as pi-conjugated systems. Polaronic properties due to the Jahn-Teller type effects are mainly discussed. (1) A Su-Schrieffer-Heeger type electron-phonon model is applied to fullerenes: C_60 and C_70, and is solved with the adiabatic approximation to phonons. When the system (C_60 or C_70) is doped with

R. Gregory, J. A. Harvey

The modifications of dilaton black holes which result when the dilaton acquires a mass are investigated. We derive some general constraints on the number of horizons of the black hole and argue that if the product of the black hole charge $Q$ and the dilaton mass $m$ satisfies $Q m < O(1)$ then the black hole has only one horizon. We also argue that for $Q m

B. Broda

A topological quantum field theory of non-abelian differential forms is investigated from the point of view of its possible applications to description of polynomial invariants of higher-dimensional two-component links. A path-integral representation of the partition function of the theory, which is a highly on-shell reducible system, is obtained in the fram

Markus A. Luty, Raman Sundrum

We show that the pseudo Nambu--Goldstone boson contribution to the Peskin--Takeuchi electroweak parameter $S$ can be negative in a class of technicolor theories. This negative contribution can be large enough to cancel the positive techni-hadron contribution, showing that electroweak precision tests alone cannot be used to rule out technicolor as the mechani

Enrique F. Moreno

We study a fermionic coset model $G/H$ when the subgroup $H$ is not simply connected. We show that even when the fermionic zero modes impose selection rules which alters the values of the correlators, the Virasoro central charge of the theory results independent of the topological sector.

J. Schechter, A. Subbaraman

We give the general framework for adding &#34;light&#34; vector particles to the heavy hadron effective chiral Lagrangian. This has strong motivations both from the phenomenological and aesthetic standpoints. An application to the already observed $D \rightarrow \overbar{K^*} $ weak transition amplitude is discussed.

L. A. Worl, S. C. Huckett, B. I. Swanson, A. Saxena

Resonance Raman experiments on doped and photoexcited single crystals of mixed-halide $MX$ complexes ($M$=Pt; $X$=Cl,Br) clearly indicate charge separation: electron polarons preferentially locate on PtBr segments while hole polarons are trapped within PtCl segments. This polaron selectivity, potentially very useful for device applications, is demonstrated t

J. Tinka Gammel, K. Yonemitsu A. Saxena, A. R. Bishop, H. Röder

We discuss the consequences of both electron-phonon and electron-electron couplings in 1D and 2D multi-band (Peierls-Hubbard) models. After briefly discussing various analytic limits, we focus on (Hartree-Fock and exact) numerical studies in the intermediate regime for both couplings, where unusual spin-Peierls as well as long-period, frustrated ground state

J. Tinka Gammel, D. K. Campbell, E. Y. Loh,

When electron-electron correlations are important, it is often necessary to use exact numerical methods, such as Lanczos diagonalization, to study the full many-body Hamiltonian. Unfortunately, such exact diagonalization methods are restricted to small system sizes. We show that if the Hubbard $U$ term is replaced by a ``periodic Hubbard&#34; term, the full

Sumathi Rao

In this set of lectures, we give a pedagogical introduction to the subject of anyons. We discuss 1) basic concepts in anyon physics, 2) quantum mechanics of two anyon systems, 3) statistical mechanics of many anyon systems, 4) mean field approach to many anyon systems and anyon superconductivity, 5) anyons in field theory and 6) anyons in the Fractional Quan

T. S. Evans

The properties of the various types of bosonic Green functions at finite temperature in the zero energy limit are considered in the light of recent work.

T. S. Evans

A new time contour is used to derive real-time thermal field theory. Unlike previous path integral approaches, no contributions to the generating functional are dropped.

Supriya Kar, Alok Kumar, Gautam Sengupta

It is shown that the asymmetric chiral gauging of the WZW models give rise to consistent string backgrounds. The target space structure of the ${[{SL(2,\Re)/ {SO(1,1)}}]}_L \bigotimes {[{SL(2,\Re)/U(1)}]}_R$ model is analyzed and the presence of a hidden isometry in this background is demonstrated. A nonlinear coordinate transformation is obtained which tran

C. N. Pope, X. J. Wang

We explicitly demonstrate that the unitary representations of the $w_\infty$ algebra and its truncations are just the unitary representations of the Virasoro algebra.

E. Bergshoeff, H. J. Boonstra, M. de Roo

We perform a systematic investigation of free-scalar realisations of the Za\-mo\-lod\-chi\-kov $W_3$ algebra in which the operator product of two spin-three generators contains a non-zero operator of spin four which has vanishing norm. This generalises earlier work where such an operator was required to be absent. By allowing this spin-four null operator we

Xiang Shen

Recently, models of two-dimensional dilaton gravity have been shown to admit classical black-hole solutions that exhibit Hawking radiation at the semi-classical level. These classical and semi-classical analyses have been performed in conformal gauge. We show in this paper that a similar analysis in the light--cone gauge leads to the same results. Moreover,

Matthew H. Austern

Renormalization group analyses show that the three running gauge coupling constants of the Standard Model do not become equal at any energy scale. These analyses have not included any effects of the Higgs boson&#39;s self-interaction. In this paper, I examine whether these effects can modify this conclusion.

Rohini M. Godbole, Probir Roy, Xerxes Tata

The detectability at LEP 200 of explicit $R$-parity breaking by tau-number $(L_τ)$ violating operators is considered. The assumption of $L_τ$-violation is motivated by the relative lack of constraints on such couplings but similar considerations apply to explicit $L_e$- or $L_μ$-violation. The $LSP$, now unstable, and not necessarily neutral, decays via $L_τ

Greg W. Anderson, Stuart Raby, Savas Dimopoulos, Lawrence Hall

The fermion mass and mixing angle predictions of a recently proposed framework are investigated for large b and $τ$ Yukawa couplings. A new allowed region of parameters is found for this large $\tan β$ case. The two predictions which are substantially altered, $m_t$ and $\tan β$, are displayed, including the dependence on the inputs $|V_{cb}|$, $m_c$, $m_b$

Mark Bowick, Paul Coddington, Leping Han, Geoffrey Harris

We present the results of a large-scale simulation of a Dynamically Triangulated Random Surface with extrinsic curvature embedded in three-dimensional flat space. We measure a variety of local observables and use a finite size scaling analysis to characterize as much as possible the regime of crossover from crumpled to smooth surfaces.

J. Tinka Gammel, D. K. Campbell

Using parameter values relevant to polyacetylene and its finite polyene analogs, we determine, via exact finite size diagonalization of a 1D Peierls-Hubbard model, the relaxed geometry and optical absorption spectra of several states of interest in optical experiments (the singlet ($1^1A_g$) and triplet ($1^3B_u$) ground states, the singlet one ($n^1B_u$) an

Vladimir Privman

Diffusion-limited reaction A+A->inert with anisotropic hopping on the d=1 lattice, is solved exactly for a simultaneous updating, discrete time-step dynamics. Diffusion-dominated processes slow down as the anisotropy increases. For large times or large anisotropy, one can invoke the appropriate continuum limits. In these limits the effects of the anisotropy

Carla Buzano, Alessandro Pelizzola

The Blume - Emery - Griffiths model is investigated by use of the cluster variation method in the pair approximation. We determine the regions of the phase space where reentrant phenomenon takes place. Two regions are found, depending on the sign of the reduced quadrupole - quadrupole coupling strength $ξ$. For negative $ξ$ we find Para-Ferro-Para and Ferro-

Alessandro Pelizzola, Corrado Topi

Coherent states for a general Lie superalgebra are defined following the method originally proposed by Perelomov. Algebraic and geometrical properties of the systems of states thus obtained are examined, with particular attention to the possibility of defining a Kähler structure over the states supermanifold and to the connection between this supermanifold a

R. Casalbuoni, A. Deandrea, N. Di Bartolomeo, R. Gatto

On the basis of an effective lagrangian incorporating approximate chiral symmetry and heavy-quark spin and flavor symmetries, and by use of information on leptonic decays, we estimate the effective $D^\star Dπ$ coupling.

M. Temple-Raston, D. Alexander

We compute the low-energy classical differential scattering cross-section for BPS $SU(2)$ magnetic monopoles using the geodesic approximation to the actual dynamics and 16K parallel processors on a CM2. Numerical experiments suggest that the quantum BPS magnetic monopole differential cross-section is well-approximated by the classical BPS magnetic monopole d

Philippe Gregoire, Marc Henneaux

The hamiltonian BRST-anti-BRST theory is developed in the general case of arbitrary reducible first class systems. This is done by extending the methods of homological perturbation theory, originally based on the use of a single resolution, to the case of a biresolution. The BRST and the anti-BRST generators are shown to exist. The respective links with the

Shun&#39;ya Mizoguchi

We study the Turaev-Viro invariant as the Euclidean Chern-Simons-Witten gravity partition function with positive cosmological constant. After explaining why it can be identified as the partition function of 3-dimensional gravity, we show that the initial data of the TV invariant can be constructed from the duality data of a certain class of rational conforma

P. P. Kulish

The physical interpretation of the main notions of the quantum group theory (coproduct, representations and corepresentations, action and coaction) is discussed using the simplest examples of $q$-deformed objects (quantum group $F_q(GL(2))$, quantum algebra $sl_q(2)$, $q$-oscillator and $F_q$-covariant algebra.) Appropriate reductions of the covariant algebr

Patrick J. O&#39;Donnell, Humphrey K. K. Tung

We show that the exclusive decay $B\rightarrow K^{\ast}γ$ can be related to the semileptonic decay $B\rightarrowρe\barν$ using heavy-quark symmetry and $SU(3)$ flavor symmetry. A direct measurement of the $q^{2}$-spectrum for the semileptonic decay can provide relevant information for the exclusive rare decay.

R. Casalbuoni, A. Deandrea, N. Di Bartolomeo, R. Gatto

We modify a chiral effective lagrangian recently suggested to describe interactions of the light pseudoscalars with mesons containing a heavy quark, so as to incorporate light vector resonances, such as $ρ$, etc. The modification uses the hidden gauge symmetry approach. As a preliminary example we present an application to the semileptonic $D\to K^\star$ dec

Sumantra Chakravarty, Ajit Mohan Srivastava

We simulate the production of vortices in a first order phase transition at finite temperature. The transition is carried out by randomly nucleating critical bubbles and the effects of thermal fluctuations (which could be relevant for vortex production) are represented by randomly nucleating subcritical bubbles. Our results show that the presence of subcriti

E. Canessa, A. Calmetta

In an attempt to find generic features on the fractal growth of Au films deposited on Ru(001), a simple simulation model based on irreversible diffusion-limited aggregation (DLA) is discussed. Highly irregular two-dimensional dentritic islands of Au particles that gradually grow on a larger host lattice of Ru particles and have fractal dimension d_{f}~ 1.70

E. Canessa, V. L. Nguyen

An attempt to determine theoretically the highly non-linear current-voltage (I-V) characteristics of polycrystalline semiconductors, such as ZnO-based varistors, is made from the electrical properties of individual grain boundaries under dc bias. The role played by the fluctuations of double Schottky barrier heights at grain interfaces on driving electrical

G. Aldazabal, I. Allekotte, E. Andrés, C. Núñez

$N=2$ coset models of the type $SU(m+1)/SU(m)\times U(1)$ with nondiagonal modular invariants for both $SU(m+1)$ and $SU(m)$ are considered. Poincaré polynomials of the corresponding chiral rings of these algebras are constructed. They are used to compute the number of chiral generations of the associated string compactifications. Moddings by discrete symmet

D. Dalmazi

Recent results for tree amplitudes for the $N=2$ noncritical strings are presented and compared with the critical case. Arguments are given which indicate a certain discontinuity in passing from the $\hat c < 1$ model (in a Coulomb gas representation) to the $\hat c = 1$ critical case.

Avner Landver

Let $κ$ be a regular cardinal. Consider the Baire numbers of the spaces $(2^θ)_κ$ (functions from $θ$ to 2 and the less than $κ$ topology) for various $θ\geq κ$. Let l be the number of such different Baire numbers. Models of set theory with l=1 or l=2 are known and it is also known that l is finite. We show here that if $κ> ω$, then l could be any given fini

John Preskill

I review the information loss paradox that was first formulated by Hawking, and discuss possible ways of resolving it. All proposed solutions have serious drawbacks. I conclude that the information loss paradox may well presage a revolution in fundamental physics. (To appear in the proceedings of the International Symposium on Black Holes, Membranes, Wormhol

A. Jevicki, J. P. Rodrigues, A. J. van Tonder

We study the correspondence between the linear matrix model and the interacting nonlinear string theory. Starting from the simple matrix harmonic oscillator states, we derive in a direct way scattering amplitudes of 2-dimensional strings, exhibiting the nonlinear equation generating arbitrary N-point tree amplitudes. An even closer connection between the mat

J. A. Harvey, A. Strominger

This review is based on lectures given at the 1992 Trieste Spring School on String Theory and Quantum Gravity and at the 1992 TASI Summer School in Boulder, Colorado.

P. P. Kulish, E. K. Sklyanin

Quadratic algebras related to the reflection equations are introduced. They are quantum group comodule algebras. The quantum group $F_q(GL(2))$ is taken as the example. The properties of the algebras (center, representations, realizations, real forms, fusion procedure etc) as well as the generalizations are discussed.

A. Cohen, A. Nelson

Requiring that the baryon number of the universe be generated by anomalous electroweak interactions places strong constraints on the minimal supersymmetric standard model. In particular, the electric dipole moment of the neutron must be greater than $10^{-27}$e-cm. Improvement of the current experimental bound on the neutron&#39;s electric dipole moment by o

Howard Georgi

I describe a technicolor model (without walking) of all interactions up to energies of the order of 1000~TeV. The low energy extended technicolor model has the CTSM form. But at intermediate energy scales, additional interactions are required to give the KM mixing. I discuss the characteristic flavor changing neutral current interactions arising from this fl

Jihn E. Kim

The $μ$ term in the supersymmetric standard model is known to&#34; be nonzero. Supersymmetry breaking at the intermediate scale may provide the needed $μ$ term and the invisible axion. A possible solution of this $μ$ problem in superstring models is also discussed.

E. Calzetta, M. Sakellariadou

We present a class of exact solutions to the constraint equations of General Relativity coupled to a Klein - Gordon field, these solutions being isotropic but not homogeneous. We analyze the subsequent evolution of the consistent Cauchy data represented by those solutions, showing that only certain special initial conditions eventually lead to successfull In

Boro Grubisic, Vincent Moncrief

We present new evidence in support of the Penrose&#39;s strong cosmic censorship conjecture in the class of Gowdy spacetimes with $T^3$ spatial topology. Solving Einstein&#39;s equations perturbatively to all orders we show that asymptotically close to the boundary of the maximal Cauchy development the dominant term in the expansion gives rise to curvature s

Yan-Chr Tsai, Yonathan Shapir

Substrate disorder effects on the scaling properties of growing crystalline surfaces in solidification or epitaxial deposition processes are investigated. Within the harmonic approach there is a phase transition into a low-temperature (low-noise) superrough phase with a continuously varying dynamic exponent z>2 and a non-linear response. In the presence of t

Arianna Montorsi, Alessandro Pelizzola

We propose here an alternative interpretation of the fermi-linarization approach to interacting electron systems, based on the requirement that the coefficients of the linearized operators are Clifford-like variables, whose anticommutator equals an unknown constant $c$. We apply the approximation to the Falicov-Kimball model, explicitly solving the self-cons

M. Arjunwadkar, G. Baskaran, R. Basu, V. N. Muthukumar

We present results obtained (by exact diagonalization) for the problem of two t-J planes with an interlayer coupling $t_\perp$. Our results for small hole concentrations show that in-plane superconducting correlations are enhanced by $t_\perp$. When the constraint on double occupancy in the t-J model is relaxed, the enhancement disappears. These results illu

David H. Fremlin, Saharon Shelah

In a series of papers, M.Talagrand, the second author and others investigated at length the properties and structure of pointwise compact sets of measurable functions. A number of problems, interesting in themselves and important for the theory of Pettis integration, were solved subject to various special axioms. It was left unclear just how far the special

Vitali D. Milman, Nicole Tomczak-Jaegermann

The new class of Banach spaces, so-called asymptotic $l_p$ spaces, is introduced and it is shown that every Banach space with bounded distortions contains a subspace from this class. The proof is based on an investigation of certain functions, called enveloping functions, which are intimately connected with stabilization properties of the norm.

Jörg Brendle

We study the relationship between Amoeba forcing (the partial order which generically adds a measure one set of random reals) and projective measurability. Given a universe V of set theory and a forcing notion P in V we say that V is Sigma^1_n - P - absolute iff for every Sigma^1_n-sentence phi with parameters in V we have V models phi iff V^P models phi. We

Jörg Brendle, Haim Judah

We discuss the relationship between perfect sets of random reals, dominating reals, and the product of two copies of the random algebra B. Recall that B is the algebra of Borel sets of 2^omega modulo the null sets. Also given two models M subseteq N of ZFC, we say that g in omega^omega cap N is a dominating real over M iff forall f in omega^omega cap M there

Eric Carlen, Elliott Lieb

Optimal hypercontractivity bounds for the fermion oscillator semigroup are obtained. These are the fermion analogs of the optimal hypercontractivity bounds for the boson oscillator semigroup obtained by Nelson. In the process, several results of independent interest in the theory of non-commutative integration are established. {}.

M. Gasperini, J. Maharana, G. Veneziano

Generalizing our previous work, we show how $O(d,d)$ transformations can be used to &#34;boost away&#34; in new dimensions the physical singularities that occur generically in cosmological and/or black-hole string backgrounds. As an example, we show how a recent model by Nappi and Witten can be made singularity-free via $O(3,3)$ boosts involving a fifth dime

S. Govindarajan

The BRST cohomology analysis of Lian and Zuckerman leads to physical states at all ghost number for $c<1$ matter coupled to Liouville gravity. We show how these states are related to states at ghost numbers zero(pure vertex operator states -- DK states) and ghost number one(ring elements) by means of descent equations. These descent equations follow from the

Richard F. Lebed

Mass splittings between isodoublet meson pairs and between $0^{-}$ and $1^{-}$ mesons of the same valence quark content are computed in a detailed nonrelativistic model. The field theoretic expressions for such splittings are shown to reduce to kinematic and Breit-Fermi terms in the nonrelativistic limit. Algebraic results thus obtained are applied to the sp

J. F. Amundson, C. G. Boyd, E. Jenkins, M. Luke

The implications of chiral $SU(3)_L \times SU(3)_R$ symmetry and heavy quark symmetry for the radiative decays $D^{*0}\to D^0γ$, $D^{*+}\to D^+γ$, and $D_s^*\to D_sγ$ are discussed. Particular attention is paid to $SU(3)$ violating contributions of order $m_q^{1/2}$. Experimental data on these radiative decays provide constraints on the $D^* Dπ$ coupling.

M. B. Voloshin

It is shown that the technique recently suggested by Lowell Brown for summing the tree graphs at threshold can be extended to calculate the loop effects. Explicit result is derived for the sum of one-loop graphs for the amplitude of threshold production of $n$ on-mass-shell particles by one virtual in the unbroken $\lambda \phi^4$ theory. It is also found th

Peter Cho, Howard Georgi

Electromagnetic interactions are incorporated into Heavy Hadron Chiral Perturbation Theory. Short and long distance magnetic moment contributions to the chiral Lagrangian are identified, and $M1$ radiative decays of heavy vector mesons and sextet baryons are studied. Using recent CLEO $D^*$ branching fraction ratio data, we fit the meson coupling to the axia

W. Daniel Garretson, George B. Field, Sean M. Carroll

The existence of large-scale magnetic fields in galaxies is well established, but there is no accepted mechanism for generating a primordial field which could grow into what is observed today. We discuss a model which attempts to account for the necessary primordial field by invoking a pseudo-Goldstone boson coupled to electromagnetism. The evolution of this

G. Valencia

We discuss anomalous gauge boson couplings at hadron supercolliders. We review the usual description of these couplings, as well as the studies of a strongly interacting electroweak symmetry breaking sector. We present an effective field theory formulation of the problem that relates the two subjects, and that allows a consistent and systematic analysis. We

P. Gondolo, G. Gelmini, S. Sarkar

We derive constraints on the relic abundance of a generic particle of mass $\sim~1-10^{14}$ TeV which decays into neutrinos at cosmological epochs, using data from the Fréjus and IMB nucleon decay detectors and the Fly&#39;s Eye air shower array. The lifetime of such unstable particles which may constitute the dark matter today is bounded to be greater than

A. M. Green, C. Michael, J. E. Paton

Four-quark potentials for $SU(2)$ are evaluated in the static limit with the quenched approximation -- using a lattice of $16^3\times 32$ and $β=2.4$. The four quarks are restricted to the corners of rectangles with sides upto seven lattice spacings long. The results are analysed in terms of a strategy based on interquark two-body potentials -- as advocated

H. J. de Vega, A. V. Mikhailov, N. Sanchez

Exact and explicit string solutions in de Sitter spacetime are found. (Here, the string equations reduce to a sinh-Gordon model). A new feature without flat spacetime analogy appears: starting with a single world-sheet, several (here two) strings emerge. One string is stable and the other (unstable) grows as the universe grows. Their invariant size and energ

A. H. Chamseddine, G. Felder, J. Fröhlich

We study general relativity in the framework of non-commutative differential geometry. In particular, we introduce a gravity action for a space-time which is the product of a four dimensional manifold by a two-point space. In the simplest situation, where the Riemannian metric is taken to be the same on the two copies of the manifold, one obtains a model of